Chem 111 Evening Exam #3

Transcription

1 * Enter your answers on the bubble sheet. Turn in all sheets. * This exam is composed of 25 questions on 7 pages total. Go initially through the exam and answer the questions you can answer quickly. Then go back and try the ones that are more challenging to you and/or that require calculations. As discussed in the course syllabus, honesty and integrity are absolute essentials for this class. In fairness to others, dishonest behavior will be dealt with to the full extent of University regulations. I hereby state that all answers on this exam are my own and that I have neither gained unfairly from others nor have I assisted others in obtaining an unfair advantage on this exam. E = h = hc H E atom n = R hc H n 2 1 ml = 1 cm 3 a Some common ions: PO 4 3 NO 2 SO 3 Signature CN CH 3 CO 2 NO 3 SO 4 CO 3 h = 6.626x10 34 J s c = x10 8 m s 1 N = 6.022x10 23 mol 1 R H = 1.097x10 7 m 1 PERIOIC TABLE OF THE ELEMENTS 1A 2A 3B 4B 5B 6B 7B 8B 8B 8B 1B 2B 3A 4A 5A 6A 7A 8A 1 H Li Na K Rb Cs Fr (223) 4 Be Mg Ca Sr Ba Ra Sc Y La Ac Ti Zr Hf Unq (261) 23 V Nb Ta Unp (262) 24 Cr Mo W Unh (263) 25 Mn Tc (99) 75 Re Uns (262) 26 Fe Ru Os Uno (265) 27 Co Rh Ir 28 Ni Pd Pt Une (266) a 29 Cu Ag Au Zn Cd Hg B Al Ga In Tl C Si Ge Sn Pb N P As Sb Bi O S Se Te Po (209) 9 F Cl Br I At (210) 2 He Ne Ar Kr Xe Rn (222)

2 Solubility Rules for some ionic compounds in water 1. All sodium (Na + ), potassium (K + ), and ammonium (NH 4 + ) salts are SOLUBLE. 2. All nitrate (NO 3 ), acetate (CH 3 CO 2 ), chlorate (ClO 3 ), and perchlorate (ClO 4 ) salts are SOLUBLE. 3. All chloride (Cl ), bromide (Br ), and iodide (I ) salts are SOLUBLE -- EXCEPT those also containing: lead, silver, or mercury (I) (Pb 2+,Ag +, Hg 2+ ) which are NOT soluble. 4. All sulfate (SO 4 2- ) salts are SOLUBLE - - EXCEPT those also containing: calcium, silver, mercury (I), strontium, barium, or lead (Ca 2+, Ag +, Hg 2 2+, Sr 2+, Ba 2+, Pb 2+ ) which are NOT soluble. 5. Hydroxide (OH ) and oxide (O ) compounds are NOT SOLUBLE -- EXCEPT those also containing: sodium, potassium, or barium (Na +, K +, Ba 2+ ) which are soluble. 6. Sulfide (S ) salts are NOT SOLUBLE -- EXCEPT those also containing: sodium, potassium, ammonium, or barium (Na +, K +, NH 4 +, Ba 2+ ) which are soluble. 7. Carbonate (CO 3 ) and phosphate (PO 4 3 ) salts are NOT SOLUBLE -- EXCEPT those also containing: sodium, potassium, or ammonium (Na +, K +, NH 4 + ), which are soluble. Identify the choice that best completes the statement or answers the question. 1. What is the hybridization of the central nitrogen atom in nitrite ion, NO 2? a. sp b. sp 2 c. sp 3 d. sp 3 d e. sp 3 d 2 B TOP: 9.2 Valence Bond Theory 2. For which of the following molecules does the central carbon atom have sp 2 hybridization? a. Cl 2 CO b. CHCl 3 c. CS 2 d. CH 2 Cl 2 e. HCN A TOP: 9.2 Valence Bond Theory 3. What is the molecular geometry around a central atom that is sp 2 hybridized, has three sigma bonds, and one pi bond? a. trigonal-planar d. T-shaped b. trigonal-pyramidal e. tetrahedral c. bent A TOP: 9.2 Valence Bond Theory 4. Which of the following characteristics apply to SO 2? 1. polar bonds 2. nonpolar molecule 3. linear molecular shape 4. sp hybridized a. 1 only d. 1, 2, and 3 b. 1 and 2 e. 1, 2, 3, and 4 c. 3 and 4 A TOP: 9.2 Valence Bond Theory

3 5. A molecular orbital that decreases the electron density between two nuclei is said to be. a. hybridized c. antibonding e. nonpolar b. bonding d. pi-bonding C TOP: 9.3 Molecular Orbital Theory 6. The following valence molecular orbital energy level diagram is appropriate for which one of the listed species? * 2p * 2p 2p 2p * 2s 2s a. B 2 b. C 2 c. N 2 d. O 2 C TOP: 9.3 Molecular Orbital Theory e. F 2 7. Which picture best represents the electronic distribution in orbital g? a. c. e. b. d. 8. The diatomic AB above is CN -. What is the overall bond order? a. 1.0 b. 1.5 c. 2.0 d. 2.5 e. 3.0 E

4 9. The picture at right depicts which type of orbital hybridization? a. sp c. sp 3 e. sp 3 d 2 b. sp 2 d. sp 3 d A 10. In the molecule 2-pentenoic acid, which most closely measures the C 3 -C 4 -H angle? a. 90 c. 120 e. 180 b. 109 d. 145 B 11. Each carbon atom in CH 3 CH 3 requires what type of orbital hybridization? a. sp c. sp 3 e. no hybridization b. sp 2 d. sp 4 C 12. An alcohol will initially react with the molecule below at which position? 13. Which carbon center below is most deficient in electrons? B

5 14. Which of the following statements is/are correct? 1. Water soluble ionic compounds, such as NaCl, are strong electrolytes. 2. Some molecular compounds, such as HCl, are strong electrolytes. 3. Some molecular compounds, such as acetic acid, are weak electrolytes. a. 1 only c. 3 only e. 1, 2, and 3 b. 2 only d. 1 and 2 E TOP: 3.5 Ions and Molecules in Aqueous Solutions 15. Which one of the following compounds is a nonelectrolyte when dissolved in water? a. KI c. MgCl 2 e. F 2 b. MgBr 2 d. Zn(NO 3 ) 2 E TOP: 3.5 Ions and Molecules in Aqueous Solutions 16. A precipitate will form when aqueous Pb(NO 3 ) 2 is added to an aqueous solution of a. Cu(NO 3 ) 2 c. NaCH 3 CO 2 e. CaBr 2 b. NaNO 3 d. Ca(ClO 4 ) 2 E TOP: 3.6 Precipitation Reactions 17. Formic acid, HCO 2 H, is a weak acid. Write a net ionic equation for the reaction of aqueous formic acid and aqueous potassium hydroxide. a. HCO 2 H(aq) + KOH(aq) K + (aq) + HCO 2 (aq) + H 2 O( ) b. HCO 2 H(aq) + H 2 O(aq) HCO 2 (aq) + H 3 O + ( ) c. H + (aq) + OH (aq) H 2 O( ) d. HCO 2 H(aq) + OH (aq) HCO 2 (aq) + H 2 O( ) e. H + (aq) + KOH(aq) K + (aq) + H 2 O( ) TOP: 3.7 Acids and Bases 18. Write a balanced chemical equation for the reaction of aqueous solutions of potassium sulfide and nitric acid. a. K 2 S(aq) + 2 HNO 3 (aq) 2 KH(aq) + S(NO 3 ) 2 (g) b. K 2 S(aq) + HNO 3 (aq) HS(g) + K 2 NO 3 (aq) c. K 2 S(aq) + 2 HNO 3 (aq) S(s) + H 2 (g) + 2 KNO 3 (aq) d. K 2 S(aq) + 2 HNO 3 (aq) 2 K(s) + H 2 (g) + S(NO 3 ) 2 (g) e. K 2 S(aq) + 2 HNO 3 (aq) H 2 S(g) + 2 KNO 3 (aq) E TOP: 3.8 Gas-Forming Reactions 19. Which species is oxidized in the reaction below? I (aq) + ClO (aq) IO (aq) + Cl (aq) a. ClO c. I e. none b. H 2 O d. IO C TOP: 3.9 Oxidation-Reduction Reactions

6 20. What is the oxidation number of iodine in potassium periodate, KIO 4? a. 1 b. 0 c. +3 d. +5 e. +7 E TOP: 3.9 Oxidation-Reduction Reactions 21. Consider the reaction FeCO HNO 3 Fe(NO 3 ) 2 + CO 2 + H 2 O This reaction is best classified as a. oxidation-reduction d. acid-base b. gas-evolving e. gas-evolving and acid-base c. precipitation E 22. Alka seltzer is a combination of citric acid, C 6 H 8 O 7, and NaHCO 3. They react in your glass to form C 6 H 7 O 7, H2 O, and CO2. What is the oxidation number of the carbon pointed to by the arrow? a. 4 b. 3 c. 2 d. 1 e Mixing Na 2 S with BaCl 2 in water leads to precipitation of a. a Cl - salt d. nothing precipitates b. a Ba 2+ salt e. everything precipitates c. a Na + salt What is the oxidation number of chromium in Cr 2 O 7? a. +2 c. +5 e. +7 b. +4 d What course is this? a) Bio 152 c) Sports 01 e) Chem 111 b) Election 08 d) Math E